The invention encompasses a system for high level expression of human cyclooxygenase-2 protein including a high expression human cyclooxygenase-2 (COX-2) cDNA and mammalian expression vectors.
Non-steroidal, antiinflammatory drugs exert most of their antiinflammatory, analgesic and antipyretic activity and inhibit hormone-induced uterine contractions and certain types of cancer growth through inhibition of prostaglandin G/H synthase, also known as cyclooxygenase. Until recently, only one form of cyclooxygenase had been characterized, this corresponding to cyclooxygenase-1 (COX-1), a constitutive enzyme originally identified in bovine seminal vesicles. More recently the gene for an inducible form of cyclooxygenase (cyclooxygenase-2; COX-2)) has been cloned, sequenced and characterized from chicken, murine and human sources. Cyclooxygnase-2 is distinct from the cyclooxygenase-1 which has also been cloned, sequenced and characterized from sheep, murine and human sources. Cyclooxygenase-2 is rapidly and readily inducible by a number of agents including mitogens, endotoxin, hormones, cytokines and growth factors. Given that prostaglandins have both physiological and pathological roles, we have concluded that the constitutive enzyme, cyclooxygenase-1, is responsible for much of the endogenous basal release of prostaglandins and hence is important in their physiological functions which include the maintenance of gastrointestinal integrity and renal blood flow. In contrast the inducible form of the enzyme, cyclooxygenase-2, is mainly responsible for the pathological effects of prostaglandins where rapid induction of the enzyme would occur in response to such agents as inflammatory agents, hormones, growth factors, and cytokines. Thus, a selective inhibitor of cyclooxygenase-2 will have similar antiinflammatory, antipyretic and analgesic properties of a conventional non-steroidal antiinflammatory drug (NSAID), will inhibit hormone-induced uterine contractions and will have potential anti-cancer effects, but will also have a diminished ability to induce some of the mechanism-based side effects. In particular, such a selective inhibitor should have a reduced potential for gastrointestinal toxicity, a reduced potential for renal side effects, a reduced effect on bleeding times and possibly a reduced ability to induce asthma attacks in aspirin-sensitive asthmatic subjects.
Accordingly, it is an object of this invention to provide assays and materials to identify and evaluate pharmacological agents that are potent inhibitors of cyclooxygenase-2 and cyclooxygenase-2 activity.
It is also an object of this invention to provide assays and materials to identify and evaluate pharmacological agents that preferentially or selectively inhibit cyclooxygenase-2 and cyclooxygenase-2 activity over cyclooxygenase-1 and cyclooxygenase-1 activity.